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Old 03-21-2012, 01:47 PM   #1
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Differing circuits/amperage share same gang box?


Hi all - I live in Massachusetts, and wiring a new addition to my house. Does anyone know if it's code-compliant to install a 30 amp receptacle from 1 circuit, & a 15 amp receptacle from a different circuit in the same 2-gang box?

I know I could install each in their own box, but prefer the simpler appearance of a 2-gang.

Thank you!

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Old 03-21-2012, 01:51 PM   #2
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Differing circuits/amperage share same gang box?


Not a problem as long a box fill isnt exceeded. It's the voltage that is the deciding factor, not amperage. When this is an issue is when you try to run low voltage cable with line voltage. Most low voltage cable isn't rated for 120v, so it must be seperated

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Old 03-21-2012, 02:05 PM   #3
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Differing circuits/amperage share same gang box?


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Originally Posted by jimmy21
Not a problem as long a box fill isnt exceeded. It's the voltage that is the deciding factor, not amperage. When this is an issue is when you try to run low voltage cable with line voltage. Most low voltage cable isn't rated for 120v, so it must be seperated
Great-thx! My plan is for one receptacle to be fed via 10/2 wire, the other with 14/2. Both at 120V. How can I determine if this will exceed box fill?
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Old 03-21-2012, 03:29 PM   #4
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Differing circuits/amperage share same gang box?


What is the useage for the 30 amp 120 volt receptacle?
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Old 03-21-2012, 03:43 PM   #5
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Differing circuits/amperage share same gang box?


You may not be able to find a cover plate for this.

Like RJ, I would like to know what the 120 volt 30 amp receptacle is for.
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Old 03-21-2012, 07:32 PM   #6
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Differing circuits/amperage share same gang box?


The 30 amp is for 1 of two separately-located receptacles that are dedicated to two large window AC units. Great point about the cover plate - never thought about that! I'll have to scour the Internet for one...

Thanks everyone, for your wisdom :-)
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Old 03-21-2012, 07:59 PM   #7
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Differing circuits/amperage share same gang box?


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The 30 amp is for 1 of two separately-located receptacles that are dedicated to two large window AC units. Great point about the cover plate - never thought about that! I'll have to scour the Internet for one...

Thanks everyone, for your wisdom :-)
And it is highly unlikely the two receptacles will fit in the same enclosure. If they will fit at all. Take a look at a standard 30 amp dryer receptacle. It has to be by itself, all alone in the box.
This is done for a reason. To keep people from doing what you propose.
Separate circuit, separate box and plates for each circuit in YOUR instance.
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Old 03-22-2012, 02:41 PM   #8
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Differing circuits/amperage share same gang box?


I would put them in separate boxes too. I just installed a 30 amp RV plug in my barn. I had to put it in a two-gang box by itself because it was just just slightly too big for the 1-gang box I had. I installed in an outdoor box with outdoor cover, so I may have had a little less room, but I don't know if both the 30-amp and 15-amp outlets will fit.

And as was said, you'll have a hard time finding a cover for the box. I did a quick search at the Leviton site. The closest I found was this one, but your 30-amp outlet will not fit the hole:
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Old 03-23-2012, 08:47 AM   #9
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Differing circuits/amperage share same gang box?


Really appreciate everyone's advice. I recalculated the 2 AC window unit amperage, and have determined that an 8k BTU unit and a 10k BTU Unit will fit on a dedicated 20 amp circuit. No more 30 amp to try to jam into boxes. Thank again, all!
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Old 03-23-2012, 11:54 AM   #10
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Differing circuits/amperage share same gang box?


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Really appreciate everyone's advice. I recalculated the 2 AC window unit amperage, and have determined that an 8k BTU unit and a 10k BTU Unit will fit on a dedicated 20 amp circuit. No more 30 amp to try to jam into boxes. Thank again, all!
You don't figure if they will fit as you say. Each unit has its requirements listed right on the nameplate. This is how you size the circuit. To the manufacturers specs.
Do not add up the current (amps) and size the circuit this way. Better to do it right the first time.

Besides. How did we get from 30 amp to 20 amp requirement. Makes no sense. Its either 20 or 30. What does it say on the nameplate for each unit?
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Old 03-23-2012, 12:46 PM   #11
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Differing circuits/amperage share same gang box?


Quote:
Originally Posted by m2234 View Post
Really appreciate everyone's advice. I recalculated the 2 AC window unit amperage, and have determined that an 8k BTU unit and a 10k BTU Unit will fit on a dedicated 20 amp circuit. No more 30 amp to try to jam into boxes. Thank again, all!
An 8k and/or 10k A/C would NOT be allowed on a 30A circuit anyway since they would both have 15A plugs on them.
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Old 03-25-2012, 10:46 AM   #12
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Differing circuits/amperage share same gang box?


I haven't purchased the AC units yet. But manufacturer specs indicate both pull a combined 15.5 amps, which is less than 80% of a 20 amp circuit. They are both 110/120 V plugs. Did I calculate correctly?
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Old 03-25-2012, 10:49 AM   #13
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Differing circuits/amperage share same gang box?


Sorry, misread the post. I don't see a problem putting both AC's on the same 20A circuit. I don't remember them drawing only 7.5 A, but I guess I don't doubt it.
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Old 03-25-2012, 10:53 AM   #14
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Differing circuits/amperage share same gang box?


How could both pull 30 amps when running at same time? One pulls 8.3 amps, the other pulls 7.2 amps. That's how I arrived at 15.5 amps total - with both running at the same time. Thx.
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Old 03-25-2012, 11:05 AM   #15
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Differing circuits/amperage share same gang box?


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How could both pull 30 amps when running at same time? One pulls 8.3 amps, the other pulls 7.2 amps. That's how I arrived at 15.5 amps total - with both running at the same time. Thx.
The starting amps may be a problem, I would use separate circuits.

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